In the field of LED discovery: reversible hydrogen can achieve high efficiency OLEDs

- Jul 20, 2017 -

In any field, research and exploration on new technology of industry scientists are always relentless in their pursuit? Recently in the field of LED has a big discovery! Reversible hydrogen can achieve efficient OLEDs!

New research has found that molecules that change their chemical structure slightly before and after launch can provide a novel and stable way to achieve efficient oleds.

The researchers studied mechanisms involving the reversible transfer of hydrogen atoms-the transfer of their cation nuclei-from one atom in the emitter to another atom in the same molecule, in order to create an environment conducive to thermally activated delayed fluorescence (TADF).

The current molecular design of TADF materials focuses on the combination of donor and receptor units. But researchers at the Center for Organic Photon and electron research at Kyushu University in Japan have proposed a method based on the intramolecular proton Transfer (ESIPT) in the excited state to achieve effective TADF without relying on the donor-acceptor scheme.

When the emitter is stimulated by optical or electrical energy, the esipt occurs spontaneously.

Quantum chemistry calculations by researchers show that TADF is unlikely to occur until the hydrogen atom is transferred. After hydrogen is transferred to different atoms in the same molecule, this creates a molecular structure capable of producing TADF. After the molecule emits light, the hydrogen shifts back to its initial atom. The molecule is then ready to begin repeating the process.

Esipt leads to the separation of the highest occupation and the lowest molecular orbital, thus achieving the luminous efficiency of TADF emission near 60%. The high external electroluminescent quantum efficiency of OLEDs using the emitter is up to 14%, indicating that an effective triplet harvesting effect can be achieved using TADF materials based on Esipt.

The researchers said it was the first demonstration of an efficient TADF observed inside and outside the device.

The molecules used in this study were initially synthesized to produce light absorbing pigments.

The study could expand and accelerate the development of various TADF materials for high-performance OLEDs.

It is only now beginning to explore the advantages of this design strategy, but one particularly promising area is related to its stability. It is known that molecules similar to this study are highly resistant to degradation, so researchers hope these molecules can help improve oleds life.